Circuit breakers can include electrical contact assemblies, which may have multiple pivotable contact arms per electrical phase. The contact arms are intended to blow apart from the stationary electrical contact due to magnetic repulsive forces generated under very high short circuit conditions. Currently, not only is there a demand to decrease the relative size of existing circuit breakers, but also to further improve their interruption speed. It is desirable that such circuit breakers interrupt as quickly as possible in order to limit damage to the protected electrical equipment and also to prevent excessive contact erosion.
Arc chutes have been used in circuit breakers in order to increase interruption speed. Arc chutes typically include stacked metal arc plates, with the top plate usually including an arc horn, which wraps over a front of some of the upper arc plates in front of the arm tips of the pivotable contact arms. One feature that has been used to increase speed at which the arc is pushed into the arc plates is by using magnetic forces augmented through the use of a slot motor. However, at lower arc currents it becomes quite difficult to push the arc into the upper arc plates, which, as has been witnessed by the inventors, results in lower arc voltage across the circuit breaker and little or no erosion of the upper arc plates.
Thus, improved mechanisms adapted to be used in circuit breakers to improve arc extinguishing performance are sought.